Having elucidated the secretory dynamics of insulin over the past ten years, we will now do likewise in terms of glucagon secretion. This will be done in normal subjects and three types of diabetics: insulinopenic, insulinotardic, and insulinoplethoric. Somatostatin, already shown to reduce blood levels in man by our group, will now be administered chronically to adult diabetics, and its effect on small vessel complications of diabetics will be carefully assessed on the basis that nearly total prevention of hyperglycemia may be expected to reduce both small and large vessel complications. The concurrent availability of a going glucagon assay, insulin assay, growth hormone assay and both a professional and technical team trained and on the job should guarantee productive work and hopefully lead to a real advance in the treatment of diabetes mellitus.